Down-Hole Swivel Sub

ABSTRACT

The present disclosure relates to a down-hole swivel sub ( 10 ) for connection in a work-string between a work-string and a down-hole apparatus, the sub comprising a first substantially cylindrical body ( 12 ) with a sleeve portion ( 22 ), a second substantially cylindrical body ( 28 ) being partially located within the sleeve portion ( 22 ) and the bodies being arranged to rotate relative to each other; and a clutch ( 90 ) disposed between said first and second substantially tubular bodies.

FIELD OF THE INVENTION

The present invention relates to down-hole tools for use in the oil and gas industry and, in especially, to a swivel sub suitable for various uses including insertion of delicate screens or liners into a wellbore, in directional drilling, or in slide drilling.

BACKGROUND TO THE INVENTION

When drilling wellbores for oil and gas production, a drill-string is used which includes various components such as the drill-bit, the down-hole assembly and the drill-pipe.

Another form of work-string may be provided which is located within a completed or nearly completed well-bore.

Both of these arrangements may be required to rotate around a central axis. The drill-bit, for example, must usually rotate in order that it abrades the seabed to form the well-bore. The rotation may be the whole of the arrangement or it may be advantageous if only part of the work or drill-string rotates, or that different sections rotate at different angular velocities and/or with different torques being exerted.

Some examples of such situations include:

-   -   Well bore cleaning while drilling     -   Slide drilling     -   Enhanced RSS     -   Stick slip mitigation     -   BHA RPM limiter     -   Torque reduction     -   Lower sand screen completions     -   Horizontal liners (cemented or non-cemented)     -   Slotted or pre-perforated liners     -   Gravel pack installations     -   TCP gun deployment     -   Fishing     -   Included in BHA for Firing jars     -   Deploying deep set packers     -   Multi-lateral completions     -   Casing exits

SUMMARY OF THE INVENTION

According to a first aspect of the present invention there is provided a down-hole swivel sub for connection in a work-string between a work-string and a down-hole apparatus, the sub comprising a first substantially cylindrical body with a sleeve portion, a second substantially cylindrical body being partially located within the sleeve portion and the bodies being arranged to rotate relative to each other; and a clutch disposed between said first and second substantially tubular bodies.

The clutch may be of any suitable form, including viscous coupling, Hele-Shaw clutches, fluid drive, wet multi-plate clutch, epicyclical planetary gear system, wet clutch, magnetic inductance and other suitable variable drive systems. Use of a viscous coupling or Hele-Shaw clutch may provide particular advantage.

The clutch may be controlled by a control device, and the control device may be actuated by a control signal, and the control signal may be in the form of a pressure differential, a flow pulse, electrical, magnetic, flow rate or other suitable means of discrete signalling.

The clutch may be actuated passively i.e. it may respond only to input torques or output resistance.

The first or second substantially cylindrical bodies may be adapted to be attachable to a drill-string or work-string. They may be further adapted to attach within a drill-string or work-string.

According to a second aspect of the present invention there is provided a method of running a downhole apparatus into a well-bore including the step of fitting an apparatus according to the first aspect of the present invention.

According to a third aspect of the present invention there is provided a drill-string or work-string for use in a wellbore including at least one apparatus according to a first aspect of the present invention.

According to a fourth aspect of the present invention there is provided an oil-rig including at least one apparatus according to a first aspect of the present invention and/or at least one drill-string or work-string according to a third aspect of the present invention.

According to a fifth aspect of the present invention there is provided a method of adapting a drill-string or work-string for use in a wellbore by fitting a clutch between two independently rotatable sections of said drill-string or work-string.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described, by way of example only, with reference to the following drawings, in which:

FIG. 1 is a side sectional elevation of a down-hole swivel sub according a first embodiment of the present invention;

FIG. 2 is a detailed view of the apparatus of FIG. 1;

FIG. 3 is a sectional view through the line A-A of FIG. 1;

FIG. 4 is a side sectional elevation of a down-hole swivel sub according a second embodiment of the present invention; and

FIG. 5 is a detailed view of the apparatus of FIG. 4.

Reference is initially made to FIG. 1 of the drawings, which illustrates a swivel sub, generally indicated by reference numeral 10, according to the first embodiment of the present invention. Sub 10 comprises a first cylindrical body 12 having at an upper end 14, a box section 16 for connecting the body 12 to a drill-pipe string (not shown). The body 12 includes a bore 18 therethrough and at a lower end 20 there is provided a sleeve 22 extending from the body 12. Located within the sleeve 22 is a bearing sleeve 24 which includes bearings 26 a,26 b to provide a rotational coupling to anything placed adjacent to the bearing sleeve 24.

Located within the bearing sleeve 24 and thus rotationally coupled to it, is an inner mandrel 28. Inner mandrel 28 is a cylindrical body having a central bore 30 located there through. At an upper end 32, distal to the bearing sleeve 24, is a pin section 34 for connecting the sub to a down-hole apparatus (not shown).

A clutch 90 is rotationally coupled between sleeve 22 and inner mandrel 28. The clutch 90 is a viscous coupling, although it will be appreciated that other suitable clutch mechanisms may be used.

Attached to the sleeve 22 is a locking sleeve 36 which may form part thereof. The locking sleeve 36 abuts an outer surface 38 of the mandrel 28. Locking sleeve 36 is preferably screwed to the sleeve 22 and has at an upper end 40 a narrowed portion 42 which has, on its outer surface 44, six teeth 46 a-f, as illustrated in FIG. 3.

Located on the outer surface 38 of the mandrel 28 is a sliding sleeve 48. The sliding sleeve 48 is arranged to travel longitudinally on the inner mandrel 28. Its passage is restricted by an abutment face 50 on the mandrel 28 and by engagement with the teeth 46 on the locking sleeve 36. At an upper end 52 of the sliding sleeve, arranged on an inner surface 54 thereof, are located six teeth 56 a-f, as illustrated in FIG. 3. Teeth 46, 56 are sized so that they can engage with each other when axially brought together.

Located around the sliding sleeve 48 are six shear pins 58. The shear pins 58 are equidistantly spaced around the sleeve 48, passing through apertures in the sleeve 48 into the inner mandrel 28. Thus, the sliding sleeve 48 is fixed to the inner mandrel 28.

In a first configuration, as shown in FIG. 1, the shear pins 58 fix the sliding sleeve 48 to the mandrel 28. The sliding sleeve 48 is located against the abutment face 50. The teeth 46, 56 are disengaged with the upper end 52 of sleeve 48 being clear of the teeth 46 on the locking sleeve 36 though there is still provided a small overlap to assist in positioning the sleeves on the sub 10. Also located on the sleeve 48 is a locking dog 60. This is a sprung pin which is biased towards the inner mandrel 28. In this embodiment, the dog 60 is compressed.

Reference is now made to FIG. 3 of the drawings, which illustrates the sub 10 of FIG. 1, in a second configuration. In FIG. 3, shear pins 58 have been sheared and the sliding sleeve 48 has been moved up so that the teeth 46,56 are completely engaged. The locking dog 60 is now located over a recess 62 on the inner mandrel 28. The dog 60 expands to locate a pin into the recess 62. With the pin located in the recess 62, the sliding sleeve 48 is prevented from movement. The locking sleeve 36, through engagement with the sliding sleeve 48, is now locked to the inner mandrel 28.

In this operation, the sub 10 is largely similar to the sub described in WO 2006/109090.

In use, sub 10 is connected to a drill-pipe string via the box section 16. A liner or screen is attached via—A liner hanging tool or running tool onto the pin section 34 at the lower end 32 of the sub 10. The sliding sleeve 48 is arranged in the configuration shown in FIG. 1, that is the sleeve is pulled back against the abutment face 50 and the shear pins 58 are mounted through the sleeve 48 into the inner mandrel 28. In this configuration the sub is unlocked and the teeth 46, 56 are clear of each other and disengaged. The inner mandrel 28 is now only connected to the top sub 10 via the bearing sleeve 24. In this way, the body 12 and the mandrel 28 can rotate independently of each other.

When run in a wellbore, the drill-pipe string at the upper end 14 of the sub 10 can be rotated, while the liner connected to the inner mandrel 28 can remain stationary. No torque will be imparted onto the liner, as it is all borne by the bearing sleeve 24. Further rotation of the drill-pipe string above the sub is achieved without tension or compression on the sub. This means that once the screen or liner is at total depth (TD), the drill string can continue to be rotated during circulation to aid in hole displacement, and cuttings or debris removal without fear of imparting rotation or torque below.

Clutch 90 allows a driving torque and rotation to be applied to the drill-pipe string above the sub 10 at or below a certain value without the driving torque and rotation being applied to the drill-pipe string below the sub 10. Increasing torque or rotational value above a certain threshold may actuate the clutch mechanism and allow torque and driving rotation to be applied below the sub 10. This would be the clutch 90 in a passive operation mode i.e. one in which it simply responded to applied rotation and/or torque applied to the drill-string.

The clutch 90 also provides a safety mechanism in that any snagging of the drill-string below the sub 10 which causes an abrupt termination of rotation would be borne by the clutch 90 and mitigates any potential damage to sub 10 or other parts of the drill-string.

A bore 92 is provided through a sidewall of the body 12 from a proximal end 90 a of the clutch through to a pressure relief mechanism 94. The pressure relief mechanism comprises a sliding piston 96 provided within a chamber 98. Any pressure build up will expand through the bore 92 and displace the piston 96.

If rotation of the liner hanger or setting tool is required, a differential pressure is induced within the sub 10. This can be done by a pressure cycle or dropping a ball from the surface of the wellbore through the bores 18 and 30 of the sub, and into a ball seat. The ball seat may be mounted in the inner mandrel 28 or, alternatively, it may be located in the liner hanging tool or running tool mounted on the pin 34 of the inner mandrel 28. On passing a ball into the bore 30, fluid can be circulated through the bore 30 to induce a pressure build up within the sub 10, pressure outside the sub on the sliding sleeve 48 will induce movement in the sleeve 48. Sufficient force of the movement will break the shear pins 58, allowing the sleeve 48 to move.

Sleeve 48 will move towards the upper end 14 of the sub 10. As the sleeve 48 moves, the teeth 56 pass between the teeth 46 on the locking sleeve 36. The engagement of the teeth 46,56 causes the sleeves 36, 48 to couple until the locking pin 60 reaches the recess 62, whereupon movement of the sliding sleeve 48 is then prevented. In this position, teeth 46, 56 are fully engaged and the sliding sleeve 48 is locked to the inner mandrel 28. Torque now imparted from the drill-pipe string will cause rotation of the body 12 and the locking sleeve 36. By virtue of the engagement of the teeth 46,56 the sliding sleeve 48 will be forced to rotate with the body 12. As the sliding sleeve 48 is locked to the inner mandrel 28, the inner mandrel will now also rotate with the body 12, thus the entire sub 10 will rotate with the drill string.

This feature can be considered an emergency device that can be used to help screen deployment running tools that perhaps will not release easily. Having an ability to rotate the running tools to free them from the running assembly, may prevent the unnecessary upward movement of the screens or liner once deployed. The lock-up feature could also be necessary if hydraulically tools were required to be released by their emergency release features, i.e., through left-hand rotation, as is the case for some liner hanger tools used for screen deployments.

In the embodiment shown, a predetermined differential pressure at the sub of around 2,500 psi is required to disengage the sliding sleeve and cause movement into the locked position. The differential pressure can be achieved by pushing up against a ball on a shearable ball seat. It could also be applied by running a retrievable plug to a profile at the bottom of the sub 10. The retrievable plug would be inserted through the bores 18 and 30 of the sub 10.

A similar ball mechanism may be used to engage or disengage the clutch 90. This would be a more active method of clutch control rather than the passive mode described above. As well as the ball mechanism, it is envisaged that the clutch 90 may be controlled by other possible means, such as pressure differential, flow pulse, electrical, magnetic, flow rate or other means of discrete signalling.

Reference is now made to FIGS. 4 and 5 of the drawings which shows a swivel sub generally indicated by reference numeral 110, according to a further embodiment of the present invention. Like parts to those of the swivel sub 10 shown in FIGS. 1 to 3, have been given the same reference numeral with the addition of 100. The embodiment in FIG. 4 is similar to the swivel sub 10 of FIGS. 1 to 3, but of a relatively simpler design. The sub 110 comprises a first cylindrical body 112 having at an upper end 114, a box section 116 for connecting the body 112 to a drill-pipe string (not shown). The body 112 includes a bore 118 there-through and at a lower end 120 there is provided a sleeve 122 extending from the body 112. Located within the sleeve 122 is a bearing sleeve 124 which includes bearings 126 a,126 b to provide a rotational coupling to anything placed adjacent to the bearing sleeve 124.

Located within the bearing sleeve 124 and thus rotationally coupled to it, is an inner mandrel 128. Inner mandrel 128 is a cylindrical body having a central bore 130 located there through. At an upper end 132, distal to the bearing sleeve 124, is a pin section 134 for connecting the sub to a down-hole apparatus (not shown).

A clutch 190 is rotationally coupled between sleeve 122 and inner mandrel 128. The clutch 190 is a viscous coupling, although it will be appreciated that other suitable clutch mechanisms may be used.

The main difference of the second embodiment from the first embodiment is the absence of the sliding sleeve 48, associated mechanisms and functionality. A simpler mechanism comprising, essentially, two rotatable bodies attached via a clutch mechanism is provided.

An advantage of the present invention is that it provides a swivel sub which allows a work-string to be rotated above the sub, while a down-hole apparatus, such as a screen, liner assembly, or drill bit below the sub is not affected by the rotation or torque.

A further advantage of the present invention is that it provides a swivel sub, wherein the rotational coupling can be selectively deployed so that, if necessary, the torque can be imparted through the sub. A yet further advantage of the present invention is that it provides a swivel sub in which relative rotation between the work-string above and down-hole apparatus, such as a screen, liner assembly, or drill bit below the sub, can be achieved without compression or tension at the sub.

Further advantages of the present invention include the ability for the upper string to be rotated independently of any down-hole apparatus that is run below without imparting any torque or rotation to the apparatus being deployed and/or allowing the upper string to be rotated faster than the apparatus being deployed with a reduction in torque transmitted from the work-string to the said apparatus.

Further still, it may allow a predetermined torque to be held on the apparatus without rotation of said apparatus being deployed by maintaining a predetermined rotational speed in the work string above.

Further still, it may allow a predetermined torque limit to be set to avoid excess torque and stall out shock loads being transmitted into down hole apparatus being deployed and/or it may allow multiple tools to be run and functioned independently in the same work string so as to allow a combination of variable speed and torque to be conveyed to many parts of the same work string.

Moreover, it may allow multiple tools to be run and functioned independently in the same work string so as to allow a combination of variable speed and torque and tool lock out to be conveyed to many parts of the same work string and/or it may allow tools to be locked to provide full 1 to 1 drive from work string to apparatus that is being deployed.

Further still, it may allow the upper string to be rotated slower than the apparatus being deployed with a reduction in torque transmitted from the work-string to the said apparatus and/or it may allow the upper string to be rotated faster than the apparatus being deployed with an increase in torque transmitted from the work-string to the said apparatus.

The present invention may find application in several applications, including:

-   -   Well bore cleaning while drilling     -   Slide drilling     -   Enhanced RSS     -   Stick slip mitigation     -   BHA RPM limiter     -   Torque reduction     -   Lower sand screen completions     -   Horizontal liners (cemented or non-cemented)     -   Slotted or pre-perforated liners     -   Gravel pack installations     -   TCP gun deployment     -   Fishing     -   Included in BHA for Firing jars     -   Deploying deep set packers     -   Multi-lateral completions     -   Casing exits

It will be appreciated that while the terms ‘upper’ and ‘lower together with ‘top’ and ‘bottom’ have been used within this specification, they are relative terms and the sub could find equal application in deviated or horizontal wellbores.

Various modifications may be made to the invention herein described without departing from the scope thereof. For instance, although the change in differential pressure has been described by the action .of a ball landing on a shearable ball seat or by running of a retrievable plug to a profile at the bottom of the sub, the movement of the sliding sleeve can also be effected by the application of hydraulics on the surface, or indeed by other mechanical means. Additionally, the embodiments described show a sub wherein the drill-pipe string can rotate relative to apparatus connected at the base of the sub during run-in, the sub could equally be set such that the sub is locked to provide through rotation during run-in, and then unlocked in a position in the wellbore. This feature may be suitable for the operation of hydraulic tools located at the base of the sub. 

1. A down-hole swivel sub for connection in a work-string between a work-string and a down-hole apparatus, the sub comprising a first substantially cylindrical body with a sleeve portion, a second substantially cylindrical body being partially located within the sleeve portion and the bodies being arranged to rotate relative to each other; and a clutch disposed between said first and second substantially tubular bodies.
 2. A down-hole swivel sub according to claim 1 wherein the clutch includes a viscous coupling.
 3. A down-hole swivel sub according to claim 1 wherein the clutch is a Hele-Shaw clutch.
 4. A down-hole swivel sub according to any preceding claim wherein the clutch is controlled by a control device.
 5. A down-hole swivel sub according to claim 4 wherein the control device is actuated by a control signal.
 6. A down-hole swivel sub according to claim 5 wherein the control signal is selected from the group comprising a pressure differential, a flow pulse, electrical, magnetic and a flow rate.
 7. A down-hole swivel sub according to claim 1 wherein the clutch is actuated passively.
 8. A down-hole swivel sub according to claim 1 wherein the first or second substantially cylindrical bodies are adapted to be attachable to a drill-string or work-string.
 9. A down-hole swivel sub according to claim 1 wherein the first or second substantially cylindrical bodies are adapted to attach within a drill-string or work-string.
 10. A drill-string or work-string for use in a wellbore including at least one apparatus according to claim
 1. 11. An oil-rig comprising at least one apparatus according to claim
 1. 12. A method of running a downhole apparatus into a well-bore including the step of fitting an apparatus according to claim
 1. 13. A method of adapting a drill-string or work-string for use in a wellbore comprising the step of fitting a clutch between two independently rotatable sections of said drill-string or work-string. 